Babel (protocol)

The Babel routing protocol is a distance-vector routing protocol for Internet Protocol packet-switched networks that is designed to be robust and efficient on both wireless mesh networks and wired networks. Babel is described in RFC 8966.^[1]

Babel routing protocol logo.

Babel is based on the ideas in Destination-Sequenced Distance Vector routing (DSDV), Ad hoc On-Demand Distance Vector Routing (AODV), and Cisco's Enhanced Interior Gateway Routing Protocol (EIGRP), but uses different techniques for loop avoidance. Babel has provisions for using multiple dynamically computed metrics; by default, it uses hop-count on wired networks and a variant of expected transmission count on wireless links, but can be configured to take radio diversity into account ^[2] or to automatically compute a link's latency and include it in the metric.^[3]

Babel operates on IPv4 and IPv6 networks. It has been reported to be a robust protocol and to have fast convergence properties.^[4][5]

In October 2015, Babel was chosen as the mandatory-to-implement protocol by the IETF Homenet working group, albeit on an Experimental basis.^[6] In June 2016, an IETF working group was created whose main goal is to produce a standard version of Babel.^[7] In January 2021, the working group produced a standard version of Babel,^[1] then proceeded to publish a number of extensions, including for authentication, source-specific routing, and routing of IPv4 through IPv6 routers.^[8]

Implementations

babeld

Developer(s)	Juliusz Chroboczek
Repository	github.com/jech/babeld
Operating system	Linux, BSD, Mac OS X
Type	Routing software
License	MIT License
Website	www.irif.fr/~jch/software/babel/

Several implementations of Babel are freely available:

• The standalone "reference" implementation
• A complete reimplementation integrated in the BIRD routing platform^[9]
• A version integrated into the FRR routing suite^[10] (previously Quagga, from which Babel has been removed^[11]).
• A tiny, stub-only subset implementation^[12]
• A minimal, IPv6-only reimplementation in Python^[13]
• An independent implementation in Java,^[14] part of the freeRouter project^[15]

Both BIRD and the reference version have support for Source-specific routing^[16] and for cryptographic authentication.^[17]